V8 API Reference, 7.2.502.16 (for Deno 0.2.4)
elements.h
1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef V8_ELEMENTS_H_
6 #define V8_ELEMENTS_H_
7 
8 #include "src/elements-kind.h"
9 #include "src/keys.h"
10 #include "src/objects.h"
11 
12 namespace v8 {
13 namespace internal {
14 
15 class JSTypedArray;
16 
17 // Abstract base class for handles that can operate on objects with differing
18 // ElementsKinds.
20  public:
21  explicit ElementsAccessor(const char* name) : name_(name) { }
22  virtual ~ElementsAccessor() = default;
23 
24  const char* name() const { return name_; }
25 
26  // Returns a shared ElementsAccessor for the specified ElementsKind.
27  static ElementsAccessor* ForKind(ElementsKind elements_kind) {
28  DCHECK_LT(static_cast<int>(elements_kind), kElementsKindCount);
29  return elements_accessors_[elements_kind];
30  }
31 
32  // Checks the elements of an object for consistency, asserting when a problem
33  // is found.
34  virtual void Validate(JSObject* obj) = 0;
35 
36  // Returns true if a holder contains an element with the specified index
37  // without iterating up the prototype chain. The caller can optionally pass
38  // in the backing store to use for the check, which must be compatible with
39  // the ElementsKind of the ElementsAccessor. If backing_store is nullptr, the
40  // holder->elements() is used as the backing store. If a |filter| is
41  // specified the PropertyAttributes of the element at the given index
42  // are compared to the given |filter|. If they match/overlap the given
43  // index is ignored. Note that only Dictionary elements have custom
44  // PropertyAttributes associated, hence the |filter| argument is ignored for
45  // all but DICTIONARY_ELEMENTS and SLOW_SLOPPY_ARGUMENTS_ELEMENTS.
46  virtual bool HasElement(JSObject* holder, uint32_t index,
47  FixedArrayBase backing_store,
48  PropertyFilter filter = ALL_PROPERTIES) = 0;
49 
50  inline bool HasElement(JSObject* holder, uint32_t index,
51  PropertyFilter filter = ALL_PROPERTIES);
52 
53  // Note: this is currently not implemented for string wrapper and
54  // typed array elements.
55  virtual bool HasEntry(JSObject* holder, uint32_t entry) = 0;
56 
57  // TODO(cbruni): HasEntry and Get should not be exposed publicly with the
58  // entry parameter.
59  virtual Handle<Object> Get(Handle<JSObject> holder, uint32_t entry) = 0;
60 
61  virtual bool HasAccessors(JSObject* holder) = 0;
62  virtual uint32_t NumberOfElements(JSObject* holder) = 0;
63 
64  // Modifies the length data property as specified for JSArrays and resizes the
65  // underlying backing store accordingly. The method honors the semantics of
66  // changing array sizes as defined in EcmaScript 5.1 15.4.5.2, i.e. array that
67  // have non-deletable elements can only be shrunk to the size of highest
68  // element that is non-deletable.
69  virtual void SetLength(Handle<JSArray> holder, uint32_t new_length) = 0;
70 
71 
72  // If kCopyToEnd is specified as the copy_size to CopyElements, it copies all
73  // of elements from source after source_start to the destination array.
74  static const int kCopyToEnd = -1;
75  // If kCopyToEndAndInitializeToHole is specified as the copy_size to
76  // CopyElements, it copies all of elements from source after source_start to
77  // destination array, padding any remaining uninitialized elements in the
78  // destination array with the hole.
79  static const int kCopyToEndAndInitializeToHole = -2;
80 
81  // Copy all indices that have elements from |object| into the given
82  // KeyAccumulator. For Dictionary-based element-kinds we filter out elements
83  // whose PropertyAttribute match |filter|.
84  virtual void CollectElementIndices(Handle<JSObject> object,
85  Handle<FixedArrayBase> backing_store,
86  KeyAccumulator* keys) = 0;
87 
88  inline void CollectElementIndices(Handle<JSObject> object,
89  KeyAccumulator* keys);
90 
91  virtual Maybe<bool> CollectValuesOrEntries(
92  Isolate* isolate, Handle<JSObject> object,
93  Handle<FixedArray> values_or_entries, bool get_entries, int* nof_items,
94  PropertyFilter filter = ALL_PROPERTIES) = 0;
95 
96  virtual MaybeHandle<FixedArray> PrependElementIndices(
97  Handle<JSObject> object, Handle<FixedArrayBase> backing_store,
98  Handle<FixedArray> keys, GetKeysConversion convert,
99  PropertyFilter filter = ALL_PROPERTIES) = 0;
100 
101  inline MaybeHandle<FixedArray> PrependElementIndices(
103  GetKeysConversion convert, PropertyFilter filter = ALL_PROPERTIES);
104 
105  virtual void AddElementsToKeyAccumulator(Handle<JSObject> receiver,
106  KeyAccumulator* accumulator,
107  AddKeyConversion convert) = 0;
108 
109  virtual void TransitionElementsKind(Handle<JSObject> object,
110  Handle<Map> map) = 0;
111  virtual void GrowCapacityAndConvert(Handle<JSObject> object,
112  uint32_t capacity) = 0;
113  // Unlike GrowCapacityAndConvert do not attempt to convert the backing store
114  // and simply return false in this case.
115  virtual bool GrowCapacity(Handle<JSObject> object, uint32_t index) = 0;
116 
117  static void InitializeOncePerProcess();
118  static void TearDown();
119 
120  virtual void Set(Handle<JSObject> holder, uint32_t entry, Object* value) = 0;
121 
122  virtual void Add(Handle<JSObject> object, uint32_t index,
123  Handle<Object> value, PropertyAttributes attributes,
124  uint32_t new_capacity) = 0;
125 
126  static Handle<JSArray> Concat(Isolate* isolate, Arguments* args,
127  uint32_t concat_size, uint32_t result_length);
128 
129  virtual uint32_t Push(Handle<JSArray> receiver, Arguments* args,
130  uint32_t push_size) = 0;
131 
132  virtual uint32_t Unshift(Handle<JSArray> receiver, Arguments* args,
133  uint32_t unshift_size) = 0;
134 
135  virtual Handle<JSObject> Slice(Handle<JSObject> receiver, uint32_t start,
136  uint32_t end) = 0;
137 
138  virtual Handle<Object> Pop(Handle<JSArray> receiver) = 0;
139 
140  virtual Handle<Object> Shift(Handle<JSArray> receiver) = 0;
141 
142  virtual Handle<NumberDictionary> Normalize(Handle<JSObject> object) = 0;
143 
144  virtual uint32_t GetCapacity(JSObject* holder,
145  FixedArrayBase backing_store) = 0;
146 
147  virtual Object* Fill(Handle<JSObject> receiver, Handle<Object> obj_value,
148  uint32_t start, uint32_t end) = 0;
149 
150  // Check an Object's own elements for an element (using SameValueZero
151  // semantics)
152  virtual Maybe<bool> IncludesValue(Isolate* isolate, Handle<JSObject> receiver,
153  Handle<Object> value, uint32_t start,
154  uint32_t length) = 0;
155 
156  // Check an Object's own elements for the index of an element (using SameValue
157  // semantics)
158  virtual Maybe<int64_t> IndexOfValue(Isolate* isolate,
159  Handle<JSObject> receiver,
160  Handle<Object> value, uint32_t start,
161  uint32_t length) = 0;
162 
163  virtual Maybe<int64_t> LastIndexOfValue(Handle<JSObject> receiver,
164  Handle<Object> value,
165  uint32_t start) = 0;
166 
167  virtual void Reverse(JSObject* receiver) = 0;
168 
169  virtual void CopyElements(Isolate* isolate, Handle<FixedArrayBase> source,
170  ElementsKind source_kind,
171  Handle<FixedArrayBase> destination, int size) = 0;
172 
173  virtual Object* CopyElements(Handle<Object> source,
174  Handle<JSObject> destination, size_t length,
175  uint32_t offset = 0) = 0;
176 
177  virtual Handle<FixedArray> CreateListFromArrayLike(Isolate* isolate,
178  Handle<JSObject> object,
179  uint32_t length) = 0;
180 
181  virtual void CopyTypedArrayElementsSlice(JSTypedArray* source,
182  JSTypedArray* destination,
183  size_t start, size_t end) = 0;
184 
185  protected:
186  friend class LookupIterator;
187 
188  // Element handlers distinguish between entries and indices when they
189  // manipulate elements. Entries refer to elements in terms of their location
190  // in the underlying storage's backing store representation, and are between 0
191  // and GetCapacity. Indices refer to elements in terms of the value that would
192  // be specified in JavaScript to access the element. In most implementations,
193  // indices are equivalent to entries. In the NumberDictionary
194  // ElementsAccessor, entries are mapped to an index using the KeyAt method on
195  // the NumberDictionary.
196  virtual uint32_t GetEntryForIndex(Isolate* isolate, JSObject* holder,
197  FixedArrayBase backing_store,
198  uint32_t index) = 0;
199 
200  virtual PropertyDetails GetDetails(JSObject* holder, uint32_t entry) = 0;
201  virtual void Reconfigure(Handle<JSObject> object,
202  Handle<FixedArrayBase> backing_store, uint32_t entry,
203  Handle<Object> value,
204  PropertyAttributes attributes) = 0;
205 
206  // Deletes an element in an object.
207  virtual void Delete(Handle<JSObject> holder, uint32_t entry) = 0;
208 
209  // NOTE: this method violates the handlified function signature convention:
210  // raw pointer parameter |source_holder| in the function that allocates.
211  // This is done intentionally to avoid ArrayConcat() builtin performance
212  // degradation.
213  virtual void CopyElements(JSObject* source_holder, uint32_t source_start,
214  ElementsKind source_kind,
215  Handle<FixedArrayBase> destination,
216  uint32_t destination_start, int copy_size) = 0;
217 
218  private:
219  static ElementsAccessor** elements_accessors_;
220  const char* name_;
221 
222  DISALLOW_COPY_AND_ASSIGN(ElementsAccessor);
223 };
224 
225 void CheckArrayAbuse(Handle<JSObject> obj, const char* op, uint32_t index,
226  bool allow_appending = false);
227 
228 V8_WARN_UNUSED_RESULT MaybeHandle<Object> ArrayConstructInitializeElements(
229  Handle<JSArray> array, Arguments* args);
230 
231 // Called directly from CSA.
232 void CopyFastNumberJSArrayElementsToTypedArray(Address raw_context,
233  JSArray* source,
234  JSTypedArray* destination,
235  uintptr_t length,
236  uintptr_t offset);
237 void CopyTypedArrayElementsToTypedArray(JSTypedArray* source,
238  JSTypedArray* destination,
239  uintptr_t length, uintptr_t offset);
240 void CopyTypedArrayElementsSlice(JSTypedArray* source,
241  JSTypedArray* destination, uintptr_t start,
242  uintptr_t end);
243 
244 } // namespace internal
245 } // namespace v8
246 
247 #endif // V8_ELEMENTS_H_
Definition: v8.h:56
Definition: libplatform.h:13
Definition: v8.h:3740